Hair transplantation procedures are well-known, and typically involve (in a patient having male pattern baldness) harvesting donor hair grafts from the side and back fringe areas (donor areas) of the patient's scalp, and implanting them in a bald area (recipient area). Historically, the harvested grafts were relatively large (3-5 mm), although more recently, the donor grafts may be single follicular units. In particular, “follicular units” (also referred to herein as FU or FUs) are naturally occurring aggregates of 1-3 (and much less commonly, 4-5) closely spaced hair follicles that are distributed randomly over the surface of the scalp.
The follicular units may be classified, or “typed,” based on the number of hairs in the unit and identified in shorthand as an “F1” for a single hair follicular unit, an “F2” for a two hair follicular unit and so on for follicular units with 3-5 hairs. In some cases of multiple hair follicular units, the hairs may appear to emanate from a single follicle or point in the skin. In other cases, the hairs may exit the skin surface at slightly spaced apart positions, but converge into a single follicular unit beneath the skin. Referring to FIG. 1, a print of a digital image of an exemplary section of a human scalp 11 having a variety of types of follicular units is shown. For example, the follicular unit 13 has two hairs and is therefore an F2, while follicular unit 15 is an F1 since it has only a single hair. Similarly, follicular unit 17 appears to be an F3 having three hairs.
There are several reasons it is important and desirable to identify and classify follicular units based on the number of hairs in the follicular unit. For one, it is preferable to transplant certain classes of follicular units into specific regions of the scalp. For example, single hair follicular units (F1s) are commonly implanted along the hairline that frames the face. Follicular units with more than one hair (F2s, F3s, etc.) are commonly implanted in the mid-scalp and crown. This arrangement of follicular unit distribution is thought to produce a more natural appearing aesthetic result. Still, it may be desirable to utilize a variety of classes (also referred to as “types”) of follicular units to provide the desired attributes for the appearance of the transplanted hair. Such attributes can include the density of hair, the direction or orientation of hair, the particular mix of types of follicular units, and/or the appearance of randomness, among other possible attributes.
In addition to classifying follicular units based on the number of hairs they contain, locating and identifying the end points of each such hair in a follicular unit may also be desirable in planning and performing hair transplantation procedures. One end point, typically located on the surface of the skin and called the “tail” is the point from which one or more hairs of the follicular unit emerge from the skin. Another end point is called the “head” and corresponds to the tip of each hair of the follicular unit lying above the skin surface. Thus, a single hair follicular unit has one head while a two-hair follicular unit has two heads. Another end point of the follicular unit located below the surface of the skin is called the “bulb” and corresponds to the location/end point where one or more hairs of the follicular unit originate subcutaneously. One reason it is desirable to know the location of various relevant end points is to be able to harvest the follicular unit and then implant it without damaging it, or its parts. For example, if an F2 follicular unit has one hair longer than the other so that head 1 is located further from the skin than head 2, often it indicates that underneath the skin the principal direction of the follicular unit extends in the direction of the axis of the hair having head 1. Therefore, knowing the location of the each head of a follicular unit may help to determine the angle and orientation of the follicular unit under the skin surface, which in turn can be used to better position the harvesting tool, thereby reducing the chance of hair transection while harvesting, and also improving the efficacy of the hair transplantation procedure.
Various procedures for hair transplantation have been previously disclosed, including both manual and mechanized to certain degrees of automation. In one well-known manual process, a linear portion of the scalp is removed from a donor area by dissection with a scalpel down into the fatty subcutaneous tissue. The strip is dissected (under a microscope) into the component follicular units, which are then implanted into a recipient area in respective puncture holes made by a needle. Forceps are typically used to grasp and place the follicular unit grafts into the needle puncture locations, although other instruments and methods are known for doing so.
In “Androgenetic Alopecia” (Springer 1996), M. Inaba & Y. Inaba disclose and describe a manual method for harvesting singular follicular units by positioning a hollow punch needle having a cutting edge and interior lumen with a diameter of 1 mm, which is about equal to the diameter of critical anatomical parts of a follicular unit. The needle punch is axially aligned with an axis of a follicular unit to be extracted and then advanced into the scalp to cut the scalp about the circumference of the selected follicular unit. Thereafter, the follicular units are easily removed, e.g., using forceps, for subsequent implantation into a recipient site with a specially devised insertion needle.
U.S. Pat. No. 6,585,746 discloses an automated hair transplantation system utilizing a robot, including a robotic arm and a hair follicle introducer associated with the robotic arm. A video system is used to produce a three-dimensional virtual image of the patient's scalp, which is used to plan the scalp locations that are to receive hair grafts implanted by the follicle introducer under the control of the robotic arm. The entire disclosure of U.S. Pat. No. 6,585,746 is incorporated herein by reference.
Automated systems and methods for transplanting are also disclosed in U.S. provisional patent application Ser. Nos. 60/722,521, filed Sep. 30, 2005, 60/753,602, filed Dec. 22, 2005, and 60/764,173, filed Jan. 31, 2006, and U.S. patent application Ser. No. 11/380,903, filed Apr. 28, 2006 (now published as US 2007/0078466) and Ser. No. 11/380,907, filed Apr. 28, 2006 (now published as US 2007/0106306). The foregoing applications are all hereby incorporated by reference into the present application in their entirety.
For example, U.S. patent application Ser. No. 11/380,907, referenced above, the disclosed system comprises a robotic arm having a harvesting and/or implantation tool mounted on the arm. One or more cameras are also mounted on the arm and are used to image the work space, such as a body surface. A processor is configured to receive and process images acquired by the cameras. A controller is operatively coupled to the processor and the robotic arm. The controller controls the movement of the robotic arm based, at least in part, on the processed images acquired by the cameras and the processor. The arm is controllably moveable to position the tool at a desired orientation and position relative to the body surface to perform transplantation of hairs.
In utilizing any of these systems and methods for hair transplantation, it is desirable to first plan the transplantation to select the follicular units to be harvested and transplanted and to determine the precise location where the hairs are to be implanted. Accordingly, in planning a hair transplantation procedure, specific follicular units from a specific location on a body surface may be selected for harvesting and transplantation into a different part of the body surface. The follicular units to be transplanted may be selected based on certain criteria, for example, the type of follicular unit (i.e. F1, F2, etc.), the orientation of the hair in the follicular unit, the density of the hair, etc. However, the process of counting and characterizing each follicular unit can be tedious and time consuming. Therefore, there is a need for a system and method for classifying follicular units, including identifying the end points of each hair of the follicular unit, using an automated system.